Tag Archives: asphalt pavement

Students from BYU’s Civil Engineering program get hands-on training on asphalt tests

A countertop with baking pans, spatulas and mixers is not something you’d expect to find when you think of UDOT. But they’re all important tools that help us preserve our infrastructure in Utah.

How, you ask? On Tuesday, Jan. 27, students from Brigham Young University’s Civil Engineering program found out during a trip to Region Three’s Materials Lab in Orem.

Using oil, water, a vacuum and a lot of ovens, the students took part in hands-on training on asphalt testing and verification of asphalt mix design by baking, scooping, calculating and compacting the material.

Before paving occurs on a roadway, engineers determine the appropriate materials for the project, document the specifications for a concrete or asphalt mix and test the pavement design in the lab. These tests help ensure that the road surfaces we lay down are the most efficient, longest-lasting they can be. We believe that good roads cost less: less to build and less to maintain. Through quality assurance tests at our region labs, we maximize the value of taxpayer dollars.

Lab Manager William “Billy Bob” Larson said his lab invites students from BYU and Utah Valley University to take part in hands-on learning on a regular basis to enhance what they learn in the classroom.

“If you don’t actually get out and do it, all your learning is just words,” Larson said.

Clint Tyler, a materials technician, looks on as an asphalt sample cools before conducting further tests. This machine runs a metal wheel over the sample 20,000 times to measure its durability.

Before UDOT employees reroute traffic, before they begin paving the road and even before they put out orange cones, they are hard at work. This work requires communication between traffic signal engineers, project managers and others – but none of it would happen without the approval from the materials engineers. The behind-the-scenes work done by engineers in the materials lab ensures the durability of the road before construction begins, making the lab testing a vital part of the preconstruction process.

Steve Park, Region Three Materials Engineer, explained that the purpose of the materials lab is to test road materials for strength and durability. “We get long-lasting roads by demanding high-quality materials, and it’s our job to test those materials before they’re in the road,” Park said. “We save taxpayer money that way, because we won’t have to tear it up later.”

An asphalt sample cools following some tests. The asphalt tests conducted in the materials lab help materials technicians determine the mixture’s durability.

The materials lab has a few different functions. One function is to mix and test the materials that a contractor wants to use for a project. In this process, the materials engineers and technicians use the lab to mix the materials according to the contract specifications. After they have been mixed, the materials engineers analyze the results, and the mixtures are evaluated according to strict safety and durability standards.

After the materials engineers complete their analysis, UDOT materials technicians then test the mixes. One test assesses the durability of an asphalt mix by placing a sample in a machine that simulates a car driving on it. The machine runs a metal wheel over it 20,000 times, and it meets durability standards if the wheel creates a rut less than 10 mm deep. Another test cures concrete samples for 28 days in at least 95 percent humidity before crushing them to measure their durability.

Clint Tyler, a materials technician, said that the importance of these tests cannot be understated. “We do these tests because it’s easier to make changes now, before it’s in the road,” Tyler said. “Our roads last longer that way.”

A stack of road core samples waits to be examined. Every so often, materials technicians will take core samples of a road to determine whether or not it needs maintenance work.

A second function of the materials lab is to test the health of the roads. Every so often, materials technicians will take a core sample of a road to determine whether or not it needs maintenance work. These projects, such as resurfacing, minimize future construction by prolonging the life of the road.

“In the end, analyzing the materials and doing these tests is just as important as the construction itself,” Park said.

While materials technicians’ work will always be behind the scenes, the results they gather will continue to directly affect Utah drivers. Their hard work ensures that UDOT’s roads will provide safe and smooth travels for years to come.

UDOT hopes a new product will extend the life of asphalt pavement. This photo shows an area where flexible and conventional microsurfacing is being tested side by side.

UDOT roads are built to last. “UDOT typically designs our asphalt pavements for a 20 year design life, meaning they have the structural thickness to support 20 years worth of traffic,” says Gary Kuhl, UDOT’s Statewide Pavement Management Engineer. Once built, preservation keeps the road surface in good shape so pavement can reach or extend beyond that 20 year life.

UDOT is testing a new preservation treatment called flexible microsurfacing. Conventional microsurfacing is a thin asphalt “wearing course” that contains aggregate, emulsion and binder (usually cement) that is mixed on-site and applied to the road.

The new product has an additional ingredient – a strong, flexible type of fiber – that is intended to help the asphalt reduce cracking and resist damage from traffic and snow plows. Flexible microsurfacing uses a regular microsurfacing machine and a blower to add fibers to the conventional mix.

Fiber adds durability to conventional microsurfacing.

The two products were placed side by side on a busy arterial road in Davis County. After a two year evaluation, the flexible microsurfacing “shows little to no damage from snowplow activities and no raveling,” states a report on the test. Raveling happens when binder fails and rocks and asphalt chunks break loose. The conventional microsurfacing side shows reflective cracking (cracks from the bottom up) that stops where the flexible microsurfacing starts.

Scott Nussbaum, Materials Engineer for UDOT Region One, thinks “the initial performance is positive.” But its use is “still experimental” continues Nussbaum. UDOT will need to continue to study this product and develop specifications for its use.

UDOT engineers believe that the additive increases the toughness and durability over conventional microsurfacing to help reduce or delay cracking and resist raveling and snowplow damage. Kuhl is optimistic about the new product. “For a small extra cost we expect to get a stronger surface that will have less cracking. UDOT continues to test new ideas and will be monitoring how this one performs.”

More from Gary Kuhl: “UDOT found out a long time ago that ‘Good Roads Cost Less,’ so our approach has been to try and keep our pavements in good condition by strategically utilizing lower cost preservation treatments on a regular basis. Combined with a mix of rehabilitative overlays this has had the effect of extending the pavement life indefinitely. For the most part our reconstruction work is primarily due for widening and capacity needs, and rarely due to pavement failure needs.”